Not a whole lot of time on it yet,but I think had there been a noticeable difference in sound or a whistling noise I would of picked up on right away.Compared to the stock filter I do not know, as I have never had a stock filter on this 4R.I have no issues with it,just install and go.It does seem to have a little quicker throttle response,not sure if its a results of the filter or removal of the HC filter.